The present invention relates to a magnetic head having a thin film coil for use in a magnetic recording device and a method for producing the same, and more specifically relates to an arrangement of the thin film coil formed by thin film technology and a method for producing the same.
This type of magnetic head or thin film magnetic head has been frequently used mainly in the magnetic record disc device. Though the early type of thin film magnetic head had a drawback of relatively low magnetic output intensity due to a coil turn number, such a drawback has been recently overcome according to the improvement in thin film production technology. However, increasing the number of coil turns has caused another drawback of delay in response time or rising time of current flowing through the coil during a recording or writing operation due to the increase of coil inductance as compared to another type of ferrite magnetic head.
In order to reduce the inductance during the writing operation, for instance, the ferrite magnetic head of the Winchester type has a modified coil structure of intermediate terminal connection such that the electric current flow through a half of the entire coil length during the writing operation.
In order to realize such coil structure in the thin film coil, a single layer coil structure of duplex winding can be adopted in the thin film magnetic head (L. T. Romankiw et al, No. 465, ECS Meeting, October 1979). However, the single layer coil is limited with respect to its turn number and therefore cannot increase the output magnetic intensity.
Further, a double layer structure of a pair of thin film coils can be used such that an intermediate terminal or tap is drawn from the joint portion between an upper-layer coil and a lower-layer coil so as to cut by half the entire length of winding during the writing operation. However, in this case, the thickness of conductor films of the upper and lower layer coils must be precisely controlled to avoid imbalance between the opposite side resistances relative to the tap. Otherwise, such resistance imbalance would cause reduction in writing efficiency and increase in reading noise.